1. Field of the Invention
The present invention relates to an output control apparatus for a linear compressor and a method of the same which make it possible to obtain a better control performance without a deviation in accordance with the type of a system based on the detected magnitude of collision strength for controlling an output of a linear compressor, and in particular to an improved output control apparatus for a linear compressor and a method of the same which are capable of implementing a high efficiency by determining an accurate control target stroke time when a piston and a discharge valve collide with each other in a compressor system and constantly controlling an output of a compressor irrespective of a load applied thereto.
2. Description of the Background Art
As a method for controlling a linear compressor, a sensor less type control method is known. In this type control method, a current and voltage are fed back based on the following Equation 1 for thereby estimating a stroke of a piston, so that the linear compressor is controlled using the thus estimated stroke of the piston. ##EQU1##
where V represents a motor terminal voltage, v represents the speed of a movement unit, R represents a motor resistor, i represents a current, .alpha. represents a motor constant, and L represents a motor inductance. PA1 where x represents the motion of the movement unit.
The sensorless control method controls the size of the entire stroke.
The output of the linear compressor is involved in the size of the stroke as well as the position of the top dead point.
Therefore, when the piston arrives at the top dead point, the volume formed by the upper surface of the piston and the inner wall of the cylinder is referred to as a top dead volume. In the same stroke case, if the top dead volume is small, the output is increased, and the efficiency is enhanced.
Here, the position of the piston is computed based on the following Equation (2). EQU x=.intg.vdt (2)
Therefore, the output of the linear compressor is controlled by the size of the stroke and the position of the top dead point of the piston.
In the conventional art, when the output of the linear compressor is controlled using the stroke, the stroke may be constantly controlled. However, in this case, since the intermediate position of the piston is varied based on the load, it is impossible to implement a constant top dead point. Namely, a constant top dead volume is not obtained. Therefore, it is difficult to control the output of the linear compressor and to implement a high efficiency and constant output.